<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=njkl, initial-scale=1.0">
    <title>Document</title>
    <style type="text/css">
        .box {
            padding-left: 20px;
            padding-right: 30px;
            padding-top: 40px;
            padding-bottom: 50px;
            width: 500px;
            height: 300px;
            background: red;
        }
    </style>
</head>

<body>
    <div class="box">内边距</div>
</body>

</html>